lib/shash.c

   1 /*
   2  * Copyright (c) 2009, 2010, 2011, 2012 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <config.h>
  18 #include "openvswitch/shash.h"
  19 #include "hash.h"
  20
  21 static struct shash_node *shash_find__(const struct shash *,
  22                                        const char *name, size_t name_len,
  23                                        size_t hash);
  24
  25 static size_t
  26 hash_name(const char *name)
  27 {
  28     return hash_string(name, 0);
  29 }
  30
  31 void
  32 shash_init(struct shash *sh)
  33 {
  34     hmap_init(&sh->map);
  35 }
  36
  37 void
  38 shash_destroy(struct shash *sh)
  39 {
  40     if (sh) {
  41         shash_clear(sh);
  42         hmap_destroy(&sh->map);
  43     }
  44 }
  45
  46 /* Like shash_destroy(), but also free() each node's 'data'. */
  47 void
  48 shash_destroy_free_data(struct shash *sh)
  49 {
  50     if (sh) {
  51         shash_clear_free_data(sh);
  52         hmap_destroy(&sh->map);
  53     }
  54 }
  55
  56 void
  57 shash_swap(struct shash *a, struct shash *b)
  58 {
  59     hmap_swap(&a->map, &b->map);
  60 }
  61
  62 void
  63 shash_moved(struct shash *sh)
  64 {
  65     hmap_moved(&sh->map);
  66 }
  67
  68 void
  69 shash_clear(struct shash *sh)
  70 {
  71     struct shash_node *node, *next;
  72
  73     SHASH_FOR_EACH_SAFE (node, next, sh) {
  74         hmap_remove(&sh->map, &node->node);
  75         free(node->name);
  76         free(node);
  77     }
  78 }
  79
  80 /* Like shash_clear(), but also free() each node's 'data'. */
  81 void
  82 shash_clear_free_data(struct shash *sh)
  83 {
  84     struct shash_node *node, *next;
  85
  86     SHASH_FOR_EACH_SAFE (node, next, sh) {
  87         hmap_remove(&sh->map, &node->node);
  88         free(node->data);
  89         free(node->name);
  90         free(node);
  91     }
  92 }
  93
  94 bool
  95 shash_is_empty(const struct shash *shash)
  96 {
  97     return hmap_is_empty(&shash->map);
  98 }
  99
 100 size_t
 101 shash_count(const struct shash *shash)
 102 {
 103     return hmap_count(&shash->map);
 104 }
 105
 106 static struct shash_node *
 107 shash_add_nocopy__(struct shash *sh, char *name, const void *data, size_t hash)
 108 {
 109     struct shash_node *node = xmalloc(sizeof *node);
 110     node->name = name;
 111     node->data = CONST_CAST(void *, data);
 112     hmap_insert(&sh->map, &node->node, hash);
 113     return node;
 114 }
 115
 116 /* It is the caller's responsibility to avoid duplicate names, if that is
 117  * desirable. */
 118 struct shash_node *
 119 shash_add_nocopy(struct shash *sh, char *name, const void *data)
 120 {
 121     return shash_add_nocopy__(sh, name, data, hash_name(name));
 122 }
 123
 124 /* It is the caller's responsibility to avoid duplicate names, if that is
 125  * desirable. */
 126 struct shash_node *
 127 shash_add(struct shash *sh, const char *name, const void *data)
 128 {
 129     return shash_add_nocopy(sh, xstrdup(name), data);
 130 }
 131
 132 bool
 133 shash_add_once(struct shash *sh, const char *name, const void *data)
 134 {
 135     if (!shash_find(sh, name)) {
 136         shash_add(sh, name, data);
 137         return true;
 138     } else {
 139         return false;
 140     }
 141 }
 142
 143 void
 144 shash_add_assert(struct shash *sh, const char *name, const void *data)
 145 {
 146     ovs_assert(shash_add_once(sh, name, data));
 147 }
 148
 149 /* Searches for 'name' in 'sh'.  If it does not already exist, adds it along
 150  * with 'data' and returns NULL.  If it does already exist, replaces its data
 151  * by 'data' and returns the data that it formerly contained. */
 152 void *
 153 shash_replace(struct shash *sh, const char *name, const void *data)
 154 {
 155     size_t hash = hash_name(name);
 156     struct shash_node *node;
 157
 158     node = shash_find__(sh, name, strlen(name), hash);
 159     if (!node) {
 160         shash_add_nocopy__(sh, xstrdup(name), data, hash);
 161         return NULL;
 162     } else {
 163         void *old_data = node->data;
 164         node->data = CONST_CAST(void *, data);
 165         return old_data;
 166     }
 167 }
 168
 169 /* Searches for 'name' in 'sh'.  If it does not already exist, adds it along
 170  * with 'data' and returns NULL.  If it does already exist, replaces its data
 171  * by 'data' and returns the data that it formerly contained.
 172  *
 173  * Takes ownership of 'name'. */
 174 void *
 175 shash_replace_nocopy(struct shash *sh, char *name, const void *data)
 176 {
 177     size_t hash = hash_name(name);
 178     struct shash_node *node;
 179
 180     node = shash_find__(sh, name, strlen(name), hash);
 181     if (!node) {
 182         shash_add_nocopy__(sh, name, data, hash);
 183         return NULL;
 184     } else {
 185         free(name);
 186         void *old_data = node->data;
 187         node->data = CONST_CAST(void *, data);
 188         return old_data;
 189     }
 190 }
 191
 192 /* Deletes 'node' from 'sh' and frees the node's name.  The caller is still
 193  * responsible for freeing the node's data, if necessary. */
 194 void
 195 shash_delete(struct shash *sh, struct shash_node *node)
 196 {
 197     free(shash_steal(sh, node));
 198 }
 199
 200 /* Deletes 'node' from 'sh'.  Neither the node's name nor its data is freed;
 201  * instead, ownership is transferred to the caller.  Returns the node's
 202  * name. */
 203 char *
 204 shash_steal(struct shash *sh, struct shash_node *node)
 205 {
 206     char *name = node->name;
 207
 208     hmap_remove(&sh->map, &node->node);
 209     free(node);
 210     return name;
 211 }
 212
 213 static struct shash_node *
 214 shash_find__(const struct shash *sh, const char *name, size_t name_len,
 215              size_t hash)
 216 {
 217     struct shash_node *node;
 218
 219     HMAP_FOR_EACH_WITH_HASH (node, node, hash, &sh->map) {
 220         if (!strncmp(node->name, name, name_len) && !node->name[name_len]) {
 221             return node;
 222         }
 223     }
 224     return NULL;
 225 }
 226
 227 /* If there are duplicates, returns a random element. */
 228 struct shash_node *
 229 shash_find(const struct shash *sh, const char *name)
 230 {
 231     return shash_find__(sh, name, strlen(name), hash_name(name));
 232 }
 233
 234 /* Finds and returns a shash_node within 'sh' that has the given 'name' that is
 235  * exactly 'len' bytes long.  Returns NULL if no node in 'sh' has that name. */
 236 struct shash_node *
 237 shash_find_len(const struct shash *sh, const char *name, size_t len)
 238 {
 239     return shash_find__(sh, name, len, hash_bytes(name, len, 0));
 240 }
 241
 242 void *
 243 shash_find_data(const struct shash *sh, const char *name)
 244 {
 245     struct shash_node *node = shash_find(sh, name);
 246     return node ? node->data : NULL;
 247 }
 248
 249 void *
 250 shash_find_and_delete(struct shash *sh, const char *name)
 251 {
 252     struct shash_node *node = shash_find(sh, name);
 253     if (node) {
 254         void *data = node->data;
 255         shash_delete(sh, node);
 256         return data;
 257     } else {
 258         return NULL;
 259     }
 260 }
 261
 262 void *
 263 shash_find_and_delete_assert(struct shash *sh, const char *name)
 264 {
 265     void *data = shash_find_and_delete(sh, name);
 266     ovs_assert(data != NULL);
 267     return data;
 268 }
 269
 270 struct shash_node *
 271 shash_first(const struct shash *shash)
 272 {
 273     struct hmap_node *node = hmap_first(&shash->map);
 274     return node ? CONTAINER_OF(node, struct shash_node, node) : NULL;
 275 }
 276
 277 static int
 278 compare_nodes_by_name(const void *a_, const void *b_)
 279 {
 280     const struct shash_node *const *a = a_;
 281     const struct shash_node *const *b = b_;
 282     return strcmp((*a)->name, (*b)->name);
 283 }
 284
 285 const struct shash_node **
 286 shash_sort(const struct shash *sh)
 287 {
 288     if (shash_is_empty(sh)) {
 289         return NULL;
 290     } else {
 291         const struct shash_node **nodes;
 292         struct shash_node *node;
 293         size_t i, n;
 294
 295         n = shash_count(sh);
 296         nodes = xmalloc(n * sizeof *nodes);
 297         i = 0;
 298         SHASH_FOR_EACH (node, sh) {
 299             nodes[i++] = node;
 300         }
 301         ovs_assert(i == n);
 302
 303         qsort(nodes, n, sizeof *nodes, compare_nodes_by_name);
 304
 305         return nodes;
 306     }
 307 }
 308
 309 /* Returns true if 'a' and 'b' contain the same keys (regardless of their
 310  * values), false otherwise. */
 311 bool
 312 shash_equal_keys(const struct shash *a, const struct shash *b)
 313 {
 314     struct shash_node *node;
 315
 316     if (hmap_count(&a->map) != hmap_count(&b->map)) {
 317         return false;
 318     }
 319     SHASH_FOR_EACH (node, a) {
 320         if (!shash_find(b, node->name)) {
 321             return false;
 322         }
 323     }
 324     return true;
 325 }
 326
 327 /* Chooses and returns a randomly selected node from 'sh', which must not be
 328  * empty.
 329  *
 330  * I wouldn't depend on this algorithm to be fair, since I haven't analyzed it.
 331  * But it does at least ensure that any node in 'sh' can be chosen. */
 332 struct shash_node *
 333 shash_random_node(struct shash *sh)
 334 {
 335     return CONTAINER_OF(hmap_random_node(&sh->map), struct shash_node, node);
 336 }